Many carbohydrates and derivatives are clinically important compounds or synthetically useful intermediates. The proposed investigation will develop practical procedures for the syntheses of carbohydrates and derivatives based on enzyme-catalyzed C-C bond and C-N bond formations. Six different aldolases will be used as catalysts for the syntheses of sugar related molecules of potential use as inhibitors of target enzymes. Nucleoside phosphorylase coupled with phosphopentomutase will be used for the synthesis of nucleosides useful as antiviral agents.